Touch panels and proximity sensors are known as interfaces for a user to input information into a display device. By arranging a touch panel or proximity sensor in a display device, a user can operate input buttons or icons and the like displayed on the screen using the user's own finger or a touch pen. In addition, by arranging a touch panel or a proximity sensor in a display device, a user can scroll images displayed on the screen using the user's own finger or a touch pen.
For example, a system has been developed in which a pen sensor contacts a touch panel, and the system detects the input of the touch pen from the position where the touch pen contacts the touch panel.